Optimizing coke generation/gasification of in-situ combustion gasification process of oil for enhanced in-well hydrogen production

This study numerically investigates in-well hydrogen production through the in-situ combustion gasification (ISCG) process, emphasizing coke generation and gasification mechanisms for higher hydrogen yield. The effects of oxidizer composition and steam injection rates on coke formation, hydrogen yield, and oil recovery factor (ORF) are studied. Key findings reveal the critical role of oxidizer oxygen concentration. High oxygen environments (99.5 % O₂+0.5 % N₂) achieved peak temperatures of 650 °C after 8 h, with 6.50 cm³ of coke and 0.0013 m³ of hydrogen produced, supporting an ORF of 94.52 %. Lower oxygen concentrations (21 % O₂ + 79 % N₂) reduced the peak temperature to 430 °C, coke formation to 2.42 cm³, hydrogen production to 0.00009 m³, and ORF to 33.8 %. Nitrogen dilution hindered combustion efficiency and thermal cracking. Steam injection significantly affected combustion dynamics and hydrogen yield. At 0.0075 m³/day, hydrogen production peaked at 0.77 m³, accompanied by 62.75 cm³ of coke. Increased steam flow rates (e.g., 0.015 m³/day) diluted the reaction zone, reducing hydrogen output and coke formation to 0.65 m³ and 49.80 cm³, respectively. Steam-to-oil ratio (SOR) increased from 0.25 (0.005 m³/day) to 0.53 (0.015 m³/day), highlighting the importance of optimizing injection rates. These results highlight ISCG's potential for simultaneous hydrogen production and enhanced oil recovery.